Mechanisms underlying accuracy in fast goal-directed arm movements in man

This study investigated how accuracy is attained in fast goal-directed arm movements. Subjects were instructed to make arm extension movements over three different distances in random order, with and without visual feedback. Target width was varied proportionally with distance. Movement time was kept as short as possible, but there were well-defined limits with respect to accuracy. There appeared to be a large relative variability (variation coefficient [VC]) in the initial acceleration. The VC in the distance the hand moved during the acceleration phase was much smaller. This reduction was accompanied by a strong negative correlation between the initial acceleration and the duration of the acceleration phase. Further, the VC in the total distance moved was less than the VC in the distance moved during acceleration. This result indicates asymmetry between the acceleration and the deceleration phase. This is confirmed by the negative correlation between the distance the hand moved during acceleration and the distance it moved during deceleration. Withdrawal of visual feedback had a significant effect on movement accuracy. No differences were found in the parameters of the acceleration phase in the two feedback conditions, however. our results point to the existence of a powerful variability compensating mechanism within the acceleration phase. This mechanism seems to be independent of visual feedback; this suggests that efferent information (efference copies) and/or proprioceptive information is/are responsible for the timing of agonist and antagonist activation. The asymmetry between the acceleration and deceleration phase contributes to a reduction in the relative variability in the total distance moved. The fact that the withdrawal of visual feedback affected movement variability only during the deceleration phase indicates that visual information is used in the adjustment of antagonist activity.     

Untersuchungen zur psychischen Wirkung eines zentralen Stimulans nach verschiedenen Graden psychischer Beanspruchung

Zusammenfassung Ziel der Arbeit war die Untersuchung der Frage, ob die Wirkungsintensität eines zentralen Stimulans (2-Äthyl-amino-3-phenyl-norcamphan) abhängig ist vom Grad vorgegangener psychischer Beanspruchung.Nach einem Meßwiederholungsplan mit systematischer Permutation der Bedingungen nahm jeder von 16 Probanden an vier Versuchen teil. An einem Versuch wurde Placebo verabreicht, an drei Versuchen 2-Äthyl-amino-3-phenyl-norcamphan. Dabei wurde das Präparat entweder 1 Stunde, 3 oder 5 Stunden nach Beginn des Versuches (Beanspruchung) verabreicht.In mehreren psychologischen Leistungsvariablen und zwei Methoden zur Erfassung von subjektiven Veränderungen wurde untersucht, inwieweit die Hypothese einer Proportionalität zwischen Wirkungsintensität und Grad der Ausgangsermüdung verifiziert ist.Die Ergebnisse zeigen, daß in leistungsmäßiger Hinsicht diese Hypothese als falsifiziert anzusehen ist. Lediglich in subjektiv-erlebnismäßiger Hinsicht besteht eine gewisse Proportionalität.     

Everyday temptations: an experience sampling study of desire, conflict, and self-control

How often and how strongly do people experience desires, to what extent do their desires conflict with other goals, and how often and successfully do people exercise self-control to resist their desires? To investigate desire and attempts to control desire in everyday life, we conducted a large-scale experience sampling study based on a conceptual framework integrating desire strength, conflict, resistance (use of self-control), and behavior enactment. A sample of 205 adults wore beepers for a week. They furnished 7,827 reports of desire episodes and completed personality measures of behavioral inhibition system/behavior activation system (BIS/BAS) sensitivity, trait self-control, perfectionism, and narcissistic entitlement. Results suggest that desires are frequent, variable in intensity, and largely unproblematic. Those urges that do conflict with other goals tend to elicit resistance, with uneven success. Desire strength, conflict, resistance, and self-regulatory success were moderated in multiple ways by personality variables as well as by situational and interpersonal factors such as alcohol consumption, the mere presence of others, and the presence of others who already had enacted the desire in question. Whereas personality generally had a stronger impact on the dimensions of desire that emerged early in its course (desire strength and conflict), situational factors showed relatively more influence on components later in the process (resistance and behavior enactment). In total, these findings offer a novel and detailed perspective on the nature of everyday desires and associated self-regulatory successes and failures.     

When East meets West: a longitudinal examination of the relationship between group relative deprivation and intergroup contact in reunified Germany

Intergroup contact and group relative deprivation have both been shown to play a key role in the understanding of intergroup relations. Nevertheless, we know little about their causal relationship. In order to shed some light on the directionality and causality of the relationship between intergroup contact and group relative deprivation, we analysed responses by East and West Germans from k= 97 different cities, collected 6 (N(T)(1) = 1,001), 8 (N(T)(2) = 747), and 10 years (N(T)(3) = 565) after reunification. Multi-level cross-lagged analyses showed that group relative deprivation at T1 led to more (rather than less) intergroup contact between East and West Germans 2 years as well as 4 years later. We found no evidence for the reverse causal relationship, or moderation by group membership. Furthermore, admiration mediated the positive effect of relative deprivation on intergroup contact for both East and West Germans. This intriguing finding suggests that intergroup contact may be used as a proactive identity management strategy by members of both minority and majority groups.     

Reinstatement of fear in humans: autonomic and experiential responses in a differential conditioning paradigm

The present study investigated reinstatement of fear in humans using an aversive differential conditioning paradigm. Two neutral human face pictures were presented during habituation, acquisition, extinction, and postreinstatement phases. One picture served as a conditioned stimulus (CS) reinforced by an unconditioned stimulus (US) in the form of electrical stimulation (CS+) and the second picture as a control stimulus that was never reinforced (CS-). The prediction that in a reinstatement manipulation a previously extinguished fear response in humans can be reinstated in a reinstatement group by the mere presentation of three unpredicted electrical stimulations (USs) was tested. Participants in the control group were not exposed to unpredicted USs and no reinstatement effect was expected. Outcome measures included subjective US expectancy ratings and skin conductance responses. Results showed non-selective return of the fear response due to fear recovery associated with both CSs (CS+/CS-) in the reinstatement group. Unexpected fear recovery was observed for both CSs (CS+/CS-) in control participants. Results are discussed with respect to context conditioning, fear generalisation, and anxiety-related cognitive mechanisms underlying fear recovery after extinction.     

Toward a Cognitive-Behavioral Classification System for Mental Disorders

As is true for its predecessors, the recently published DSM-5 uses arbitrary criteria and cutoffs to define categories of mental disorders that are of questionable validity and that provide no guidance for treatment. Recently, the NIMH introduced an alternative classification system, the Research Domain Criteria (RDoC). Both the DSM-5 and the RDoC initiative make the strong assumption that psychological problems are expressions of specific latent disease entities. In contrast, the complex causal network approach conceptualizes psychological problems as mutually interacting, often reciprocally reinforcing, elements of a complex causal network. The cognitive behavioral model offers a classification framework that is compatible with the complex causal network approach and provides a treatment-relevant alternative to the latent disease model that is the basis for the DSM-5 and the RDoC initiative.     

Relationship between social anxiety and perceived trustworthiness

Four different patterns of biased ratings of facial expressions of emotions have been found in socially anxious participants: higher negative ratings of (1) negative, (2) neutral, and (3) positive facial expressions than nonanxious controls. As a fourth pattern, some studies have found no group differences in ratings of facial expressions of emotion. However, these studies usually employed valence and arousal ratings that arguably may be less able to reflect processing of social information. We examined the relationship between social anxiety and face ratings for perceived trustworthiness given that trustworthiness is an inherently socially relevant construct. Improving on earlier analytical strategies, we evaluated the four previously found result patterns using a Bayesian approach. Ninety-eight undergraduates rated 198 face stimuli on perceived trustworthiness. Subsequently, participants completed social anxiety questionnaires to assess the severity of social fears. Bayesian modeling indicated that the probability that social anxiety did not influence judgments of trustworthiness had at least three times more empirical support in our sample than assuming any kind of negative interpretation bias in social anxiety. We concluded that the deviant interpretation of facial trustworthiness is not a relevant aspect in social anxiety.     

Neurobiological correlates of cognitions in fear and anxiety: A cognitive–neurobiological information-processing model

We review likely neurobiological substrates of cognitions related to fear and anxiety. Cognitive processes are linked to abnormal early activity reflecting hypervigilance in subcortical networks involving the amygdala, hippocampus, and insular cortex, and later recruitment of cortical regulatory resources, including activation of the anterior cingulate cortex and prefrontal cortex to implement avoidant response strategies. Based on this evidence, we present a cognitive–neurobiological information-processing model of fear and anxiety, linking distinct brain structures to specific stages of information processing of perceived threat.